Novel combination of a host compound and a dopant compound and an organic electroluminescence device comprising the same

ABSTRACT

The present invention relates to a specific combination of a dopant compound and a host compound, and an organic electroluminescent device comprising the same. The organic electroluminescent device of the present invention emits yellow-green light; lowers the driving voltage of the device by improving the current characteristic of the device; and improves power efficiency and operational lifespan.

TECHNICAL FIELD

The present invention relates to a novel combination of a host compound and a dopant compound and an organic electroluminescence device comprising the same.

BACKGROUND ART

An electroluminescent (EL) device is a self-light-emitting device which has advantages in that it provides a wider viewing angle, a greater contrast ratio, and a faster response time compared to LCDs. An organic EL device was first developed by Eastman Kodak, by using small aromatic diamine molecules, and aluminum complexes as materials for forming a light-emitting layer [Appl. Phys. Lett. 51, 913, 1987].

The most important factor determining luminous efficiency in an organic EL device is the light-emitting material. The electroluminescent material includes a host material and a dopant material for purposes of functionality. Typically, a device that has very superior electroluminescent properties is known to have a structure in which a host is doped with a dopant to form an electroluminescent layer. Recently, the development of an organic EL device having high efficiency and long lifespan is being urgently called for. Particularly, taking into consideration the electroluminescent properties required of medium to large OLED panels, the development of materials very superior to conventional electroluminescent materials is urgent. In order to achieve such, a host material which functions as the solvent in a solid phase and plays a role in transferring energy should be of high purity and must have a molecular weight appropriate to enabling vacuum deposition. Also, the glass transition temperature and heat decomposition temperature should be high to ensure thermal stability, and high electrochemical stability is required to attain a long lifespan, and the formation of an amorphous thin film should become simple, and the force of adhesion to materials of other adjacent layers must be good but interlayer migration should not occur.

Until now, fluorescent materials have been widely used as a light-emitting material. However, in view of electroluminescent mechanisms, developing phosphorescent materials is one of the best methods to theoretically enhance luminous efficiency by four (4) times. Iridium(III) complexes have been widely known as dopant compounds of phosphorescent substances, including bis(2-(2′-benzothienyl)-pyridinato-N,C3′)iridium(acetylacetonate)[(acac)Ir(btp)₂], tris(2-phenylpyridine)iridium [Ir(ppy)₃] and bis(4,6-difluorophenylpyridinato-N,C2)picolinato iridium [Firpic] as red, green and blue materials, respectively. Until now, 4,4′-N,N′-dicarbazol-biphenyl (CBP) was the most widely known host material for phosphorescent substances. Further, an organic EL device of high efficiency using bathocuproine (BCP) and aluminum(III)bis(2-methyl-8-quinolinate)(4-phenylphenolate) (BAlq) for a hole blocking layer is also known.

However, there were problems affecting power efficiency, operational life span, and luminous efficiency, when applying a light-emitting material comprising conventional dopant and host compounds to an organic EL device. Further, there were difficulties with obtaining a yellow-green light emitting luminous material having excellent performance.

Korean Patent Appln. Laying-Open No. KR 10-2012-0012431 A discloses combinations of iridium complex dopant compounds, and various host compounds. However, this reference does not disclose a luminous material emitting yellow-green light.

The present inventors found that a specific combination of a luminous material containing a dopant compound and a host compound emits yellow-green light, and is suitable for manufacturing organic EL devices having high color purity, high luminance, and a long lifespan.

DISCLOSURE OF THE INVENTION Problems to be Solved

The objective of the present invention is to provide a novel combination of a dopant compound and a host compound, and an organic electroluminescent device comprising the same which lowers the driving voltage of the device by improving the current characteristic of the device; improves power efficiency and operational lifespan; and emits yellow-green light.

Solution to Problems

In order to achieve said purposes, the present invention provides a combination of one or more dopant compounds represented by the following formula 1, and one or more host compounds represented by the following formula 2:

wherein

L is selected from the following structures:

R₁ to R₉ each independently represent hydrogen, deuterium, a halogen, a substituted or unsubstituted (C1-C30)alkyl, a substituted or unsubstituted (C3-C30)cycloalkyl, a cyano, or a substituted or unsubstituted (C1-C30)alkoxy;

R₂₀₁ to R₂₁₁ each independently represent hydrogen, deuterium, a halogen, a substituted or unsubstituted (C1-C30)alkyl, or a substituted or unsubstituted (C3-C30)cycloalkyl; and

n represents an integer of 1 to 3;

wherein

ring A and ring C each independently represent an aromatic ring represented by the following formula 1a;

ring B represents a 5-membered ring represented by the following formula 1b;

L₁ and L₂ each independently represent a single bond, a substituted or unsubstituted (C6-C30)arylene, or a substituted or unsubstituted 5- to 30-membered heteroarylene;

Ar₁ and Ar₂ each independently represent hydrogen, deuterium, a halogen, a cyano, a nitro, a hydroxyl, a substituted or unsubstituted (C1-C30)alkyl, a substituted or unsubstituted (C1-C30)alkoxy, a substituted or unsubstituted (C3-C30)cycloalkyl, a substituted or unsubstituted (C6-C30)aryl, a substituted or unsubstituted tri(C1-C30)alkylsilyl, a substituted or unsubstituted tri(C6-C30)arylsilyl, or a substituted or unsubstituted 5- to 30-membered heteroaryl; or are linked to an adjacent substituent(s) to form a mono- or polycyclic, (C3-C30)alicyclic or aromatic ring whose carbon atom(s) may be replaced with at least one hetero atom selected from nitrogen, oxygen and sulfur;

R₂₁ represents hydrogen, deuterium, a halogen, a substituted or unsubstituted (C1-C30)alkyl, a substituted or unsubstituted (C6-C30)aryl, a substituted or unsubstituted 5- to 30-membered heteroaryl, —NR₁₁R₁₂—, —SiR₁₃R₁₄R₁₅—; or are linked to an adjacent substituent(s) to form a mono- or polycyclic, (C3-C30)alicyclic or aromatic ring whose carbon atom(s) may be replaced with at least one hetero atom selected from nitrogen, oxygen and sulfur;

X represents —O—, —S—, —N(R₂₂)—, —C(R₂₃R₂₄)— or —Si(R₂₅R₂₆)—;

R₁₁ to R₁₅ and R₂₂ to R₂₆ each independently represent hydrogen, deuterium, a halogen, a substituted or unsubstituted (C1-C30)alkyl, a substituted or unsubstituted (C6-C30)aryl, or a substituted or unsubstituted 5- to 30-membered heteroaryl; or are linked to an adjacent substituent(s) to form a mono- or polycyclic, (C3-C30)alicyclic or aromatic ring whose carbon atom(s) may be replaced with at least one hetero atom selected from nitrogen, oxygen and sulfur;

a and c each independently represent an integer of 0 to 4; where a or c is an integer of 2 or more, each of Ar₁, and each of Ar₂ are same or different; and

b represents an integer of 0 to 2; where b is 2, each of R₂₁ are same or different.

Effects of the Invention

The organic electroluminescent device comprising the dopant and host combination of the present invention emits yellow-green light; lowers the driving voltage of the device by improving the current characteristic of the device; and improves power efficiency and operational lifespan.

EMBODIMENTS OF THE INVENTION

Hereinafter, the present invention will be described in detail. However, the following description is intended to explain the invention, and is not meant in any way to restrict the scope of the invention.

The present invention relates to a combination of one or more dopant compounds represented by formula 1, and one or more host compounds represented by formula 2; and an organic electroluminescent device comprising the same.

The dopant compound represented by formula 1 is preferably represented by formula 3 or 4:

wherein R₁ to R₉, L, and n are as defined in formula 1.

In formulae 1, 3, and 4, R₁ to R₉ preferably each independently represent hydrogen, deuterium, a (C1-C10)alkyl unsubstituted or substituted with a halogen, an unsubstituted (C3-C7)cycloalkyl, or a (C1-C10)alkoxy unsubstituted or substituted with a halogen. R₂₀₁ to R₂₁₁ preferably each independently represent hydrogen, or an unsubstituted (C1-C10)alkyl.

The representative compounds of formula 1 include the following compounds, but are not limited thereto:

The host compound represented by formula 2 is preferably selected from formulae 5 to 10:

wherein L₁, L₂, Ar₁, Ar₂, R₂₁, X, a, b and c are as defined in formula 2.

In formulae 2, and 5 to 10, L₁ and L₂ each independently represent a single bond, a substituted or unsubstituted (C6-C30)arylene, or a substituted or unsubstituted 5- to 30-membered heteroarylene, preferably each independently represent a single bond, a substituted or unsubstituted (C6-C20)arylene, or a substituted or unsubstituted 5- to 22-membered heteroarylene, and more preferably each independently represent a single bond, a (C6-C20)arylene unsubstituted or substituted with a (C1-C6)alkyl, or an unsubstituted 5- to 22-membered heteroarylene.

Ar₁ and Ar₂ each independently represent hydrogen, deuterium, a halogen, a cyano, a nitro, a hydroxyl, a substituted or unsubstituted (C1-C30)alkyl, a substituted or unsubstituted (C1-C30)alkoxy, a substituted or unsubstituted (C3-C30)cycloalkyl, a substituted or unsubstituted (C6-C30)aryl, a substituted or unsubstituted tri(C1-C30)alkylsilyl, a substituted or unsubstituted tri(C6-C30)arylsilyl, or a substituted or unsubstituted 5- to 30-membered heteroaryl; or are linked to an adjacent substituent(s) to form a mono- or polycyclic, (C3-C30)alicyclic or aromatic ring whose carbon atom(s) may be replaced with at least one hetero atom selected from nitrogen, oxygen and sulfur, preferably each independently represent hydrogen, a substituted or unsubstituted (C1-C6)alkyl, a substituted or unsubstituted (C6-C20)aryl, a substituted or unsubstituted tri(C1-C6)alkylsilyl, a substituted or unsubstituted tri(C6-C12)arylsilyl, or a substituted or unsubstituted 5- to 22-membered heteroaryl, and more preferably each independently represent hydrogen; an unsubstituted (C1-C6)alkyl; a (C6-C20)aryl unsubstituted or substituted with a (C1-C6)alkyl or a (C6-C20)aryl; an unsubstituted tri(C1-C6)alkylsilyl; an unsubstituted tri(C6-C12)arylsilyl; or an unsubstituted 5- to 22-membered heteroaryl.

R₂₁ represents hydrogen, deuterium, a halogen, a substituted or unsubstituted (C1-C30)alkyl, a substituted or unsubstituted (C6-C30)aryl, a substituted or unsubstituted 5- to 30-membered heteroaryl, —NR₁₁R₁₂, —SiR₁₃R₁₄R₁₅; or are linked to an adjacent substituent(s) to form a mono- or polycyclic, (C3-C30)alicyclic or aromatic ring whose carbon atom(s) may be replaced with at least one hetero atom selected from nitrogen, oxygen and sulfur, preferably represents hydrogen, a substituted or unsubstituted (C6-C20)aryl, or a substituted or unsubstituted 5- to 22-membered heteroaryl, and more preferably represents hydrogen; an unsubstituted (C6-C20)aryl; or a 5- to 22-membered heteroaryl unsubstituted or substituted with a (C6-C20)aryl.

X represents —O—, —S—, —N(R₂₂)—, —C(R₂₃)(R₂₄)— or —Si(R₂₅)(R₂₆)—.

R₁₁ to R₁₅ and R₂₂ to R₂₆ each independently represent hydrogen, deuterium, a halogen, a substituted or unsubstituted (C1-C30)alkyl, a substituted or unsubstituted (C6-C30)aryl, or a substituted or unsubstituted 5- to 30-membered heteroaryl; or are linked to an adjacent substituent(s) to form a mono- or polycyclic, (C3-C30)alicyclic or aromatic ring whose carbon atom(s) may be replaced with at least one hetero atom selected from nitrogen, oxygen and sulfur, preferably each independently represent hydrogen, a substituted or unsubstituted (C1-C6)alkyl, a substituted or unsubstituted (C6-C20)aryl, or a substituted or unsubstituted 5- to 22-membered heteroaryl; or are linked to an adjacent substituent(s) to form a mono- or polycyclic, (C3-C30)alicyclic or aromatic ring, and more preferably each independently represent hydrogen; an unsubstituted (C1-C6)alkyl; an unsubstituted (C6-C20)aryl; a 5- to 22-membered heteroaryl unsubstituted or substituted with a (C6-C20)aryl; or are linked to an adjacent substituent(s) to form a mono- or polycyclic, (C3-C30)alicyclic or aromatic ring.

The representative compounds of formula 2 include the following compounds, but are not limited thereto:

Herein, “(C1-C30)alkyl(ene)” is meant to be a linear or branched alkyl(ene) having 1 to 30 carbon atoms, in which the number of carbon atoms is preferably 1 to 20, more preferably 1 to 10, and includes methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, tert-butyl, etc.; “(C2-C30) alkenyl” is meant to be a linear or branched alkenyl having 2 to 30 carbon atoms, in which the number of carbon atoms is preferably 2 to 20, more preferably 2 to 10, and includes vinyl, 1-propenyl, 2-propenyl, 1-butenyl, 2-butenyl, 3-butenyl, 2-methylbut-2-enyl, etc.; “(C2-C30)alkynyl” is a linear or branched alkynyl having 2 to 30 carbon atoms, in which the number of carbon atoms is preferably 2 to 20, more preferably 2 to 10, and includes ethynyl, 1-propynyl, 2-propynyl, 1-butynyl, 2-butynyl, 3-butynyl, 1-methylpent-2-ynyl, etc.; “(C3-C30)cycloalkyl” is a mono- or polycyclic hydrocarbon having 3 to 30 carbon atoms, in which the number of carbon atoms is preferably 3 to 20, more preferably 3 to 7, and includes cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl, etc.; “3- to 7-membered heterocycloalkyl” is a cycloalkyl having at least one heteroatom selected from B, N, O, S, P(═O), Si and P, preferably O, S and N, and 3 to 7 ring backbone atoms, and includes tetrahydrofuran, pyrrolidine, thiolan, tetrahydropyran, etc.; “(C6-C30)aryl(ene)” is a monocyclic or fused ring derived from an aromatic hydrocarbon having 6 to 30 carbon atoms, in which the number of carbon atoms is preferably 6 to 20, more preferably 6 to 15, and includes phenyl, biphenyl, terphenyl, naphthyl, fluorenyl, phenanthrenyl, anthracenyl, indenyl, triphenylenyl, pyrenyl, tetracenyl, perylenyl, chrysenyl, naphthacenyl, fluoranthenyl, etc.; “3- to 30-membered heteroaryl(ene)” is an aryl group having at least one, preferably 1 to 4 heteroatom selected from the group consisting of B, N, O, S, P(═O), Si and P, and 3 to 30 ring backbone atoms; is a monocyclic ring, or a fused ring condensed with at least one benzene ring; has preferably 5 to 20, more preferably 5 to 15 ring backbone atoms; may be partially saturated; may be one formed by linking at least one heteroaryl or aryl group to a heteroaryl group via a single bond(s); and includes a monocyclic ring-type heteroaryl such as furyl, thiophenyl, pyrrolyl, imidazolyl, pyrazolyl, thiazolyl, thiadiazolyl, isothiazolyl, isoxazolyl, oxazolyl, oxadiazolyl, triazinyl, tetrazinyl, triazolyl, tetrazolyl, furazanyl, pyridyl, pyrazinyl, pyrimidinyl, pyridazinyl, etc., and a fused ring-type heteroaryl such as benzofuranyl, benzothiophenyl, isobenzofuranyl, dibenzofuranyl, dibenzothiophenyl, benzoimidazolyl, benzothiazolyl, benzoisothiazolyl, benzoisoxazolyl, benzoxazolyl, isoindolyl, indolyl, indazolyl, benzothiadiazolyl, quinolyl, isoquinolyl, cinnolinyl, quinazolinyl, quinoxalinyl, carbazolyl, phenoxazinyl, phenanthridinyl, benzodioxolyl, etc. Further, “halogen” includes F, Cl, Br and I.

Herein, “substituted” in the expression “substituted or unsubstituted” means that a hydrogen atom in a certain functional group is replaced with another atom or group, i.e., a substituent.

The substituents of the substituted alkyl(ene), the substituted aryl(ene), the substituted heteroaryl(ene), the substituted cycloalkyl, the substituted alkoxy, the substituted trialkylsilyl, the substituted triarylsilyl, and the substituted heterocycloalkyl in the above formulae each independently are preferably at least one selected from the group consisting of deuterium; a halogen; a (C1-C30)alkyl unsubstituted or substituted with a halogen; a (C6-C30)aryl unsubstituted or substituted with a 3- to 30-membered heteroaryl; a 3- to 30-membered heteroaryl unsubstituted or substituted with a (C6-C30)aryl; a 5- to 7-membered heterocycloalkyl; a 5- to 7-membered heterocycloalkyl fused with at least one (C6-C30)aromatic ring; a (C3-C30)cycloalkyl; a (C6-C30)cycloalkyl fused with at least one (C6-C30)aromatic ring; R_(a)R_(b)R_(c)Si—; a (C2-C30)alkenyl; a (C2-C30)alkynyl; a cyano; a carbazolyl; —NR_(d)R_(e); —BR_(f)R_(g); —PR_(h)R_(i); —P(═O)R_(j)R_(k); a (C6-C30)aryl(C1-C30)alkyl; a (C1-C30)alkyl(C6-C30)aryl; R_(l)Z—; R_(m)C(═O)—; R_(m)C(═O)O—; a carboxyl; a nitro; and a hydroxyl, wherein R_(a) to R_(l) each independently represent a (C1-C30)alkyl, a (C6-C30)aryl, or a 3- to 30-membered heteroaryl; or are linked to an adjacent substituent(s) to form a mono- or polycyclic, (C3-C30)alicyclic or aromatic ring whose carbon atom(s) may be replaced with at least one hetero atom selected from the group consisting of nitrogen, oxygen and sulfur; Z represents S or O; and R_(m) represents a (C1-C30)alkyl, a (C1-C30)alkoxy, a (C6-C30)aryl, or a (C6-C30)aryloxy.

Specifically, said organic electroluminescent device comprises a first electrode; a second electrode; and at least one organic layer between said first and second electrodes. Said organic layer comprises a light-emitting layer, and said light-emitting layer comprises a combination of one or more dopant compounds represented by formula 1, and one or more host compounds represented by formula 2.

Said light-emitting layer is a layer which emits light, and it may be a single layer, or it may be a multi layer of which two or more layers are laminated.

The doping concentration, the proportion of the dopant compound to the host compound may be preferably less than 20 wt %.

Another embodiment of the present invention provides a dopant and host combination of one or more dopant compounds represented by formula 1, and one or more host compounds represented by formula 2, and an organic EL device comprising the dopant and host combination.

Still another embodiment of the present invention provides an organic layer consisting of the combination of one or more dopant compounds represented by formula 1, and one or more host compounds represented by formula 2. Said organic layer comprises plural layers. Said dopant compound and said host compound can be comprised in the same layer, or can be comprised in different layers. In addition, the present invention provides an organic EL device comprising the organic layer.

In the organic electroluminescent device according to the present invention, a mixed region of an electron transport compound and an reductive dopant, or a mixed region of a hole transport compound and an oxidative dopant may be placed on at least one surface of a pair of electrodes. In this case, the electron transport compound is reduced to an anion, and thus it becomes easier to inject and transport electrons from the mixed region to an electroluminescent medium. Further, the hole transport compound is oxidized to a cation, and thus it becomes easier to inject and transport holes from the mixed region to the electroluminescent medium. Preferably, the oxidative dopant includes various Lewis acids and acceptor compounds; and the reductive dopant includes alkali metals, alkali metal compounds, alkaline earth metals, rare-earth metals, and mixtures thereof. A reductive dopant layer may be employed as a charge generating layer to prepare an electroluminescent device having two or more electroluminescent layers and emitting white light.

Hereinafter, the compound, the preparation method of the compound, and the luminescent properties of the device will be explained in detail with reference to the following examples. However, these are just for exemplifying the embodiment of the present invention, so the scope of the present invention cannot be limited thereto.

Example 1 Preparation of Compound D-1

Preparation of Compound 1-1

After adding 2,4-dichloropyridine 5 g (34 mmol), phenyl boronic acid 16 g (135 mmol), Pd(PPh₃)₄ 3.9 g (2.4 mmol), K₂CO₃ 23 g (135 mmol), toluene 100 mL, ethanol 50 mL, and H₂O 50 mL in a flask, the mixture was stirred at 120° C. for 6 hours. Then, the reaction mixture was dried, and separated with a column to obtain compound 1-1 6.4 g (82%).

Preparation of Compound 1-2

After adding compound 1-1 4 g (17 mmol), IrCl₃ 2.3 g (7.8 mmol), 2-ethoxyethanol 60 mL, and H₂O 20 mL (2-ethoxyethanol/H₂O=3/1) in a flask, the mixture was stirred at 120° C. for 24 hours under reflux. After completing the reaction, the mixture was washed using H₂O/MeOH/Hex, and dried to obtain compound 1-2 3.0 g (56%).

Preparation of Compound 1-3

After adding compound 1-2 3.0 g (2.2 mmol), 2,4-pentanedion 0.6 g (6.5 mmol), Na₂CO₃ 1.4 g (13 mmol), and 2-ethoxyethanol 10 mL in a flask, the mixture was stirred at 110° C. for 12 hours. After completing the reaction, the produced solid was dried, and separated with a column to obtain compound 1-3 3 g (75%).

Preparation of Compound D-1

After adding compound 1-3 2.44 g (3.25 mmol), and compound 1-1 1.5 g (6.49 mmol) in a flask, glycerol was added to the mixture, and stirred for 16 hours under reflux. After the reaction, the produced solid was filtered, dried, and separated with a column to obtain compound D-1 2.5 g (87%).

Example 2 Preparation of Compound D-2 and D-8

Preparation of Compound 2-1

After adding 2,5-dibromopyridine 20 g (84 mmol), 2,4-dimethylphenyl boronic acid 15 g (101 mmol), Pd(PPh₃)₄ 4 g (3.4 mmol), Na₂CO₃ 27 g (253 mmol), toluene 240 mL, and H₂O 120 mL in a flask, the mixture was stirred at 100° C. for 12 hours. Then, the reaction mixture was extracted with ethylacetate (EA), and the moisture was removed using MgSO₄, and distilled under reduced pressure. Then, the reaction mixture was dried, and separated with a column to obtain compound 2-1 18 g (70%).

Preparation of Compound 2-2

Compound 2-2 18 g (99%) was prepared by using compound 2-1 18 g (70 mmol), and phenyl boronic acid 13 g (105 mmol) in a flask in the same manner as the synthetic method of compound 1-1.

Preparation of Compound 2-3 Compound 2-3 13 g (72%) was prepared by using compound 2-2 14 g (54 mmol), and IrCl₃ 7.5 g (24.3 mmol) in a flask in the same manner as the synthetic method of compound 1-2.

Preparation of Compound D-2

Compound D-2 2.4 g (74%) was prepared by using compound 2-3 3 g (2 mmol) in a flask in the same manner as the synthetic method of compound 1-3.

Preparation of Compound D-8

Compound D-8 1.5 g (50%) was prepared by using compound D-2 2.4 g (3 mmol) in a flask in the same manner as the synthetic method of compound D-1.

Example 3 Preparation of Compound D-9 and D-10

Preparation of Compound 3-1

Compound 3-1 16 g (79%) was prepared by using 2,5-dibromopyridine 20 g (84 mmol), and phenyl boronic acid 12 g (101 mmol) in a flask in the same manner as the synthetic method of compound 2-1.

Preparation of Compound 3-2

Compound 3-2 17 g (97%) was prepared by using compound 3-1 16 g (67 mmol), and 3,5-dimethylphenyl boronic acid 15 g (101 mmol) in a flask in the same manner as the synthetic method of compound 2-2.

Preparation of Compound 3-3

Compound 3-3 6 g (65%) was prepared by using compound 3-2 7 g (27 mmol), and IrCl₃ 3.7 g (12 mmol) in a flask in the same manner as the synthetic method of compound 2-3.

Preparation of Compound D-10

Compound D-10 5 g (81%) was prepared by using compound 3-3 6 g (4 mmol), and 2,4-pentanedion 1.2 g (12 mmol) in a flask in the same manner as the synthetic method of compound D-2.

Preparation of Compound D-9

Compound D-9 1.6 g (45%) was prepared by using compound D-10 3 g (3.7 mmol), and compound 3-2 2 g (7.4 mmol) in a flask in the same manner as the synthetic method of compound D-8.

Example 4 Preparation of Compound D-11 and D-12

Preparation of Compound 4-1

Compound 4-1 60 g (87%) was prepared by using 2,5-dibromopyridine 70 g (295.5 mmol), and phenyl boronic acid 83 g (679.6 mmol) in a flask in the same manner as the synthetic method of compound 1-1.

Preparation of Compound 4-2

Compound 4-2 44 g (92%) was prepared by using compound 4-1 40 g (380.5 mmol), and IrCl₃ 23.5 g (173 mmol) in a flask in the same manner as the synthetic method of compound 1-2.

Preparation of Compound D-11

Compound D-11 42 g (87.4%) was prepared by using compound 4-2 44 g (48 mmol), and 2,4-pentanedion 9.6 g (96 mmol) in a flask in the same manner as the synthetic method of compound 1-3.

Preparation of Compound D-12

Compound D-12 20 g (38%) was prepared by using compound D-11 42 g (80.5 mmol), and compound 4-1 20 g (161 mmol) in a flask in the same manner as the synthetic method of compound D-1.

Example 5 Preparation of Compound H-33

Preparation of Compound 5-1

After mixing 1-bromo-2-nitrobenzene 39 g (0.19 mol), dibenzo[b,d]furan-4-yl boronic acid 45 g (0.21 mol), Pd(PPh₃)₄ 11.1 g (0.0096 mol), 2 M K₂CO₃ aqueous solution 290 mL, EtOH 290 mL, and toluene 580 mL, the mixture was stirred while heating at 120° C. for 4 hours. After completing the reaction, the mixture was washed with distilled water, extracted with EA, and the organic layer was dried with anhydrous MgSO₄. Then, solvent was removed with a rotary evaporator, and the remaining product was purified using column chromatography to obtain compound 5-1 47 g (85%).

Preparation of Compound 5-2

After mixing compound 5-1 47 g (0.16 mol), triethylphosphite 600 mL, and 1,2-dichlorobenzene 300 mL, the mixture was stirred at 150° C. for 12 hours. After completing the reaction, unreacted triethylphosphite and 1,2-dichlorobenzene was removed using a distillation apparatus, and the remaining product was washed with distilled water, extracted with EA, and the organic layer was dried with anhydrous MgSO₄. Then, solvent was removed with a rotary evaporator, and the remaining product was purified using column chromatography to obtain compound 5-2 39 g (81%).

Preparation of Compound H-33

After dissolving NaH 1.9 mg (42.1 mmol) in dimethylformamide (DMF), the mixture was stirred. Then, compound 5-2 7 g (27.2 mmol) was dissolved in DMF, and added to the NaH solution which was being stirred. Then, the mixture was stirred for 1 hour. After dissolving 2-chloro-4,6-diphenylpyrimidine 8.7 g (32.6 mmol) in DMF, the mixture was stirred, and the reactant which was stirred for 1 hour was added to the mixture, and the mixture was stirred at room temperature for 24 hours. After completing the reaction, the produced solid was filtered, washed with ethylacetate, and purified using column chromatography to obtain compound H-33 3.5 g (25%).

Example 6 Preparation of Compound H-43

Compound H-43 11.3 g (78%) was prepared by using compound 5-2 7 g (27.2 mmol), and 2-chloro-4,6-diphenyl-1,3,5-triazine 8.2 g (32.6 mmol) in the same manner as the synthetic method of compound H-33.

Example 7 Preparation of Compound H-45

Preparation of Compound 7-1

Compound 7-1 10 g (32.74 mmol, 74.68%) was prepared by using dibenzo[b,d]thiophen-4-yl boronic acid 10 g (43.84 mmol) in the same manner as the synthetic method of compound 5-1.

Preparation of Compound 7-2

Compound 7-2 7 g (25.60 mmol, 78.19%) was prepared by using compound 7-1 10 g (32.74 mmol) in the same manner as the synthetic method of compound 5-2.

Preparation of Compound H-45

Compound H-45 5.6 g (40%) was prepared by using compound 7-2 7 g (25.6 mmol), and 2-chloro-4,6-diphenyl-1,3,5-triazine 8.7 g (32.6 mmol) in the same manner as the synthetic method of compound H-33.

Example 8 Preparation of Compound H-67

Compound H-67 5.3 g (49%) was prepared by using compound 7-2 7 g (25.6 mmol), and compound 8-1 8.2 g (32.6 mmol) in the same manner as the synthetic method of compound H-33.

Example 9 Preparation of Compound H-99

Compound H-99 8.6 g (46%) was prepared by using compound 5-2 7 g (27.2 mmol), and 2-chloro-4,6-di(naphthalen-1-yl)-1,3,5-triazine 15.2 g (32.6 mmol) in the same manner as the synthetic method of compound H-33.

Example 10 Preparation of Compound H-118

Preparation of Compound 10-1

After mixing 2-bromo-9,9-dimethyl-9H-fluorene 80 g (291 mmol), 2-chlorobenzeneamine 45 mL (437 mmol), Pd(OAc)₂ 2.6 g (12 mmol), P(t-Bu)₃ 12 mL (24 mmol), NaOt-Bu 70 g (728 mmol), and toluene 800 mL, the mixture was stirred while heating at 120° C. for 9 hours. After completing the reaction, the mixture was cooled to room temperature, extracted with ethylacetate 1.5 L, and the obtained organic layer was washed with distilled water 400 mL. Then, solvent was removed under reduced pressure, and the obtained solid was washed with hexane, filtered, and dried. Then, the obtained product was separated using silica gel column chromatography and recrystallization to obtain compound 10-1 70 g (75%).

Preparation of Compound 10-2

After mixing compound 10-1 70 g (218 mmol), Pd(OAc)₂ 2.4 g (11 mmol), PCy₃HBF₄ 8 g (22 mmol), Na₂CO₃ 70 g (654 mmol), and dimethylacetamide (DMA) 1.2 L, the mixture was stirred at 190° C. for 3 hours. After completing the reaction, the mixture was extracted with ethylacetate 1 L, the obtained organic layer was washed with distilled water 200 mL, and dried with anhydrous MgSO₄. Then, the organic solvent was removed under reduced pressure. Then, the obtained solid was separated using silica gel column chromatography and recrystallization to obtain compound 10-2 22 g (36%).

Preparation of Compound 10-3

After mixing compound 10-2 15 g (53 mmol), 1,4-dibromobenzene 32 mL (265 mmol), Pd(OAc)₂ 1.2 g (5 mmol), P(t-Bu)₃ 30 mL (64 mmol), NaOt-Bu 25 g (265 mmol), and toluene 300 mL, the mixture was stirred at 120° C. for 24 hours. After completing the reaction, the mixture was cooled to room temperature, extracted with ethylacetate 1.5 L, and the obtained organic layer was washed with distilled water 400 mL. Then, solvent was removed under reduced pressure, and the obtained solid was washed with hexane, filtered, and dried. Then, the obtained product was separated using silica gel column chromatography and recrystallization to obtain compound 10-3 7 g (30%).

Preparation of Compound 10-4

After dissolving compound 10-3 7 g (16 mmol) in tetrahydrofuran (THF) 100 mL, n-BuLi (2.5 M in hexane) 10 mL (24 mmol) was added to the mixture at −78° C. Then, the mixture was stirred at −78° C. for 1 hour, and B(Oi-Pr)₃ 6 mL (24 mmol) was added to the mixture. Then, the mixture was stirred for 2 hours, and the reaction was completed with aqueous ammonium chloride solution 20 mL. Then, the mixture was extracted with ethylacetate 500 mL, the obtained organic layer was washed with distilled water 200 mL, dried with anhydrous MgSO₄, and the organic solvent was removed under reduced pressure. Then, the obtained solid was separated by recrystallization to obtain compound 10-4 5 g (75%).

Preparation of Compound H-118

After mixing 2-chloro-4,6-diphenyl-1,3,5-triazine 6.5 g (0.03 mol), compound 10-4 19.2 g (0.036 mol), Pd(PPh₃)₄ 1.6 g (0.001 mol), K₂CO₃ 11 g (0.08 mol), toluene 140 mL, EtOH 35 mL, and H₂O 40 mL in a flask, the mixture was stirred at 120° C. for 12 hours. After completing the reaction, the mixture was extracted using ethylacetate, the organic layer was dried with MgSO₄, filtered, and the solvent was removed under reduced pressure. Then, the remaining product was separated with a column to obtain compound H-118 5.7 g (27%).

The detailed data of the dopant compounds prepared in Examples 1 to 4, and the dopant compounds easily prepared using Examples 1 to 4 are shown in table 1 below.

TABLE 1 Melting Point UV spectrum PL spectrum Compound Yield (%) (° C.) (nm) (nm) D-1 87 273 308 459 D-2 82 360 334 550 D-3 81 154 308 541 D-5 62 265 312 534 D-7 35 297 298 568 D-8 34 over 400 320 556 D-9 81 360 326 541 D-10 45 N/A N/A N/A D-11 92 N/A N/A N/A D-12 61 360 326 541 D-18 36 360 334 550 D-32 36 over 400 296 542 D-33 42 380 296 547 D-34 78 over 400 308 545 D-35 82 358 356 545 D-36 14 360 288 561

The detailed data of the host compounds prepared in Examples 5 to 10, and the host compounds easily prepared using Examples 5 to 10 are shown in table 2 below.

TABLE 2 Yield Melting Point UV spectrum PL spectrum Compound (%) (° C.) (nm) (nm) Mass H-33 25 260 358 471 488.5 H-34 30 259 336 463 686.9 H-36 26 350 356 429 581.7 H-38 19 329 340 420 580.7 H-41 46 225 338 482 504.3 H-43 78 312 344 385 489.5 H-44 67 249 324 458 610.7 H-45 40 324 352 482 505.7 H-46 16 339 322 411 580.7 H-48 65 253 354 480 564 H-49 50 275 340 498 538 H-50 57 288 322 492 554 H-52 60 250 334 428 680 H-53 66 278 345 501 578 H-55 45 255 334 451 581.7 H-57 89 275 320 456 580.7 H-58 72 267 334 459 610.7 H-60 46 270 344 471 593.7 H-63 42 288 370 475 745.9 H-64 28 323 N/A N/A 746.8 H-65 39 320 325 516 581.7 H-66 38 198 317 461 504.6 H-67 49 274 322 491 580.7 H-70 76 266 370 489 614 H-80 23 270 324 456 763 H-84 49 284 368 474 669.8 H-85 60 212 368 433 640 H-86 31 289 384 436 690 H-88 34 294 N/A N/A 656.8 H-89 26 245 300 460 656.8 H-91 42 328 343 481 656.8 H-92 32 294 296 467 655.2 H-94 52 241 294 464 581.7 H-95 30 293 344 469 669.8 H-96 23 238 362 429 593.7 H-97 60 280 294 468 593.7 H-99 46 324 324 495 589.7 H-100 82 250 356 448 669.8 H-104 44 357 322 460 655.8 H-109 48 278 344 395 580.7 H-112 48 221 334 396 656.8 H-118 27 240 308 451 590.7 H-120 57 261 344 431 593.7 H-121 70 255 356 521 564 H-122 12 218 358 445 640 H-123 67 261 344 521 614 H-124 47 315.4 314 530 779 H-130 16 347 324 525 669.9 H-131 34 410 258 324 670.8 H-132 36 300 258 487 686.9 H-135 74 375 340 473 687.8 H-139 23 300 336 458 580.7 H-141 36 299 332 386 805 H-144 62 294 336 479 627 H-145 69 269 324 496 552 H-146 55 254 304 532 627 H-147 89 277 336 481 578 H-148 60 306 334 427 628 H-149 22 200 392 421 703 H-150 50 243 332 424 654 H-151 51 291 346 505 588 H-152 49 222 344 497 538 H-153 77 271 308 431 614 H-154 38 251 282 519 627 H-164 24 275 344 467 610.8 H-168 55 242 344 497 614 H-169 53 275 310 495 628 H-170 75 247 360 483 512 H-173 50 305 350 502 656.8 H-174 66 305 306 407 637.8 H-175 22 238 304 465 636.8 H-176 27 274 308 463 620.7 H-179 71 173 292 509 554 H-180 79 255 338 503 512 H-181 49 309 304 427 536 H-182 49 292 290 511 538 H-183 51 256 310 504 703 H-184 77 253 308 486 703 H-185 80 231 308 487 614 H-186 55 274 312 497 654 H-187 48 336 350 508 665 H-189 69 242 310 493 614 H-190 57 190 307 390 538 H-191 47 246 346 497 614 H-192 80 247 308 487 630 H-194 47 197 362 469 538 H-195 24 291 376 447 614 H-196 80 227 344 489 462 H-197 59 283 368 495 628 H-198 26 247 386 429 538 H-199 38 285 310 490 644 H-200 70 249 310 483 588 H-202 25 255 384 423 613 H-203 40 327 310 490 614 H-204 38 280 346 484 564 H-205 68 298 310 496 613 H-206 46 288 310 487 554 H-207 46 247 356 485 478 H-208 45 267 390 501 588 H-209 37 321 384 491 640 H-210 33 267 344 497 538 H-211 47 301 344 483 653 H-212 35 289 372 479 670 H-213 75 276 344 489 588 H-214 72 265 350 386 604 H-215 69 258 324 501 637 H-216 11 217 356 489 504 H-217 57 257 342 491 538 H-218 49 290 308 498 580 H-219 63 275 308 505 630 H-220 63 289 344 479 685 H-221 22 235 336 521 668 H-222 47 298 376 482 563 H-223 49 256 372 487 614 H-225 60 328 358 490 628 H-226 65 330.5 360 507 644 H-227 55 340 324 484 640 H-229 57 227 342 487 538

Device Example 1 Production of an OLED Device Using the Organic Electroluminescent Compound According to the Present Invention

An OLED device was produced using the light emitting material according to the present invention. A transparent electrode indium tin oxide (ITO) thin film (15 Ω/sq) on a glass substrate for an organic light-emitting diode (OLED) device (Samsung Corning, Republic of Korea) was subjected to an ultrasonic washing with trichloroethylene, acetone, ethanol and distilled water, sequentially, and then was stored in isopropanol. Then, the ITO substrate was mounted on a substrate holder of a vacuum vapor depositing apparatus. N¹,N^(1′)-([1,1′-biphenyl]-4,4′-diyl)bis(N¹-(naphthalen-1-yl)-N⁴,N⁴-diphenylbenzen-1,4-diamine) was introduced into a cell of said vacuum vapor depositing apparatus, and then the pressure in the chamber of said apparatus was controlled to 10⁻⁶ torr. Thereafter, an electric current was applied to the cell to evaporate the above introduced material, thereby forming a hole injection layer having a thickness of 120 nm on the ITO substrate. Then, N4,N4,N4′,N4′-tetra([1,1′-biphenyl]-4-yl)-[1,1′-biphenyl]-4,4′-diamine was introduced into another cell of said vacuum vapor depositing apparatus, and was evaporated by applying an electric current to the cell, thereby forming a hole transport layer having a thickness of 20 nm on the hole injection layer. Thereafter, compound H-43 was introduced into one cell of the vacuum vapor depositing apparatus, as a host material, and compound D-9 was introduced into another cell as a dopant. The two materials were evaporated at different rates and were deposited in a doping amount of 12 wt % based on the total amount of the host and dopant to form a light-emitting layer having a thickness of 40 nm on the hole transport layer. Then, 2-(4-(9,10-di(naphthalen-2-yl)anthracen-2-yl)phenyl)-1-phenyl-1H-benzo[d]imidazole was introduced into one cell and lithium quinolate was introduced into another cell. The two materials were evaporated at the same rate and were deposited in a doping amount of 50 wt % each to form an electron transport layer having a thickness of 30 nm on the light-emitting layer. Then, after depositing lithium quinolate as an electron injection layer having a thickness of 2 nm on the electron transport layer, an Al cathode having a thickness of 150 nm was deposited by another vacuum vapor deposition apparatus on the electron injection layer. Thus, an OLED device was produced. All the materials used for producing the OLED device were purified by vacuum sublimation at 10⁻⁶ torr prior to use.

The produced OLED device showed a yellow-green emission having a luminance of 1470 cd/m² and a current density of 2.5 mA/cm².

Device Example 2 Production of an OLED Device Using the Organic Electroluminescent Compound According to the Present Invention

An OLED device was produced in the same manner as in Device Example 1, except for using compound H-45 as a host, and using compound D-12 as a dopant of the light emitting material.

The produced OLED device showed a yellow-green emission having a luminance of 3062 cd/m² and a current density of 5.07 mA/cm².

Device Example 3 Production of an OLED Device Using the Organic Electroluminescent Compound According to the Present Invention

An OLED device was produced in the same manner as in Device Example 1, except for using compound H-99 as a host, and using compound D-18 as a dopant of the light emitting material.

The produced OLED device showed a yellow-green emission having a luminance of 4305 cd/m² and a current density of 8.61 mA/cm².

Device Example 4 Production of an OLED Device Using the Organic Electroluminescent Compound According to the Present Invention

An OLED device was produced in the same manner as in Device Example 1, except for using compound H-67 as a host, and using compound D-9 as a dopant of the light emitting material.

The produced OLED device showed a yellow-green emission having a luminance of 1647 cd/m² and a current density of 2.86 mA/cm².

Device Example 5 Production of an OLED Device Using the Organic Electroluminescent Compound According to the Present Invention

An OLED device was produced in the same manner as in Device Example 1, except for using compound H-33 as a host, and using compound D-12 as a dopant of the light emitting material.

The produced OLED device showed a yellow-green emission having a luminance of 1164 cd/m² and a current density of 1.94 mA/cm².

Device Example 6 Production of an OLED Device Using the Organic Electroluminescent Compound According to the Present Invention

An OLED device was produced in the same manner as in Device Example 1, except for using compound H-118 as a host, and using compound D-18 as a dopant of the light emitting material.

The produced OLED device showed a yellow-green emission having a luminance of 5554 cd/m² and a current density of 15.6 mA/cm².

Device Example 7 Production of an OLED Device Using the Organic Electroluminescent Compound According to the Present Invention

An OLED device was produced in the same manner as in Device Example 1, except for using compound H-208 as a host, and using compound D-34 as a dopant of the light emitting material.

The produced OLED device showed a yellow-green emission having a luminance of 53100 cd/m² and a current density of 5.8 mA/cm².

As shown above, the organic EL device of the present invention contains a specific combination of a dopant compound and a host compound, and thus emits yellow-green light, and provides excellent current efficiency.

In addition, the organic electroluminescent compounds according to the present invention have high efficiency in transporting electrons to prevent crystallization during a device fabrication. Furthermore, the compounds have good layer formability and improve the current characteristic of the device. Therefore, they can produce an organic electroluminescent device having lowered driving voltages and enhanced power efficiency and operational lifespan.

In general, an organic EL device can emit white light by mixing 3 colors, i.e., red, green, and blue. On the other hand, when using the dopant compound and the host compound according to the present invention, it is possible to emit white color by bicolor combination with blue light. 

1. A combination of one or more dopant compound represented by the following formula 1, and one or more host compound represented by the following formula 2:

wherein L is selected from the following structures:

R₁ to R₉ each independently represent hydrogen, deuterium, a halogen, a substituted or unsubstituted (C1-C30)alkyl, a substituted or unsubstituted (C3-C30)cycloalkyl, a cyano, or a substituted or unsubstituted (C1-C30)alkoxy; R₂₀₁ to R₂₁₁ each independently represent hydrogen, deuterium, a halogen, a substituted or unsubstituted (C1-C30)alkyl, or a substituted or unsubstituted (C3-C30)cycloalkyl; and n represents an integer of 1 to 3;

wherein ring A and ring C each independently represent an aromatic ring represented by the following formula 1a; ring B represents a 5-membered ring represented by the following formula 1b;

L₁ and L₂ each independently represent a single bond, a substituted or unsubstituted (C6-C30)arylene, or a substituted or unsubstituted 5- to 30-membered heteroarylene; Ar₁ and Ar₂ each independently represent hydrogen, deuterium, a halogen, a cyano, a nitro, a hydroxyl, a substituted or unsubstituted (C1-C30)alkyl, a substituted or unsubstituted (C1-C30)alkoxy, a substituted or unsubstituted (C3-C30)cycloalkyl, a substituted or unsubstituted (C6-C30)aryl, a substituted or unsubstituted tri(C1-C30)alkylsilyl, a substituted or unsubstituted tri(C6-C30)arylsilyl, or a substituted or unsubstituted 5- to 30-membered heteroaryl; or are linked to an adjacent substituent(s) to form a mono- or polycyclic, (C3-C30)alicyclic or aromatic ring whose carbon atom(s) may be replaced with at least one hetero atom selected from nitrogen, oxygen and sulfur; R₂₁ represents hydrogen, deuterium, a halogen, a substituted or unsubstituted (C1-C30)alkyl, a substituted or unsubstituted (C6-C30)aryl, a substituted or unsubstituted 5- to 30-membered heteroaryl, —NR₁₁R₁₂, —SiR₁₃R₁₄R₁₅, or are linked to an adjacent substituent(s) to form a mono- or polycyclic, (C3-C30)alicyclic or aromatic ring whose carbon atom(s) may be replaced with at least one hetero atom selected from nitrogen, oxygen and sulfur; X represents —O—, —S—, —N(R₂₂)—, —C(R₂₃)(R₂₄)— or —Si(R₂₅)(R₂₆)—; R₁₁ to R₁₅ and R₂₂ to R₂₆ each independently represent hydrogen, deuterium, a halogen, a substituted or unsubstituted (C1-C30)alkyl, a substituted or unsubstituted (C6-C30)aryl, or a substituted or unsubstituted 5- to 30-membered heteroaryl; or are linked to an adjacent substituent(s) to form a mono- or polycyclic, (C3-C30)alicyclic or aromatic ring whose carbon atom(s) may be replaced with at least one hetero atom selected from nitrogen, oxygen and sulfur; a and c each independently represent an integer of 0 to 4; where a or c is an integer of 2 or more, each of Ar₁, and each of Ar₂ are same or different; and b represents an integer of 0 to 2; where b is 2, each of R₂₁ are same or different.
 2. The combination according to claim 1, wherein the compound represented by formula 1 is represented by formula 3 or 4:

wherein R₁ to R₉, L, and n are as defined in claim
 1. 3. The combination according to claim 1, wherein the compound represented by formula 2 is represented by any one of the following formulae 5 to 10:

wherein L₁, L₂, Ar₁, Ar₂, R₂₁, X, a, b and c are as defined in claim
 1. 4. The combination according to claim 1, wherein in formula 1, R₁ to R₉ each independently represent hydrogen, deuterium, a (C1-C10)alkyl unsubstituted or substituted with a halogen, an unsubstituted (C3-C7)cycloalkyl, or a (C1-C10)alkoxy unsubstituted or substituted with a halogen; and R₂₀₁ to R₂₁₁ each independently represent hydrogen, or an unsubstituted (C1-C10)alkyl.
 5. The combination according to claim 1, wherein in formula 2, L₁ and L₂ each independently represent a single bond, a substituted or unsubstituted (C6-C20)arylene, or a substituted or unsubstituted 5- to 22-membered heteroarylene; Ar₁ and Ar₂ each independently represent hydrogen, a substituted or unsubstituted (C1-C6)alkyl, a substituted or unsubstituted (C6-C20)aryl, a substituted or unsubstituted tri(C1-C6)alkylsilyl, a substituted or unsubstituted tri(C6-C12)arylsilyl, or a substituted or unsubstituted 5- to 22-membered heteroaryl; R₂₁ represents hydrogen, a substituted or unsubstituted (C6-C20)aryl, or a substituted or unsubstituted 5- to 22-membered heteroaryl; and R₁₁ to R₁₅ and R₂₂ to R₂₆ each independently represent hydrogen, a substituted or unsubstituted (C1-C6)alkyl, a substituted or unsubstituted (C6-C20)aryl, or a substituted or unsubstituted 5- to 22-membered heteroaryl; or are linked to an adjacent substituent(s) to form a mono- or polycyclic, (C3-C30)alicyclic or aromatic ring.
 6. The combination according to claim 1, wherein the compound represented by formula 1 is selected from the group consisting of:


7. The combination according to claim 1, wherein the compound represented by formula 2 is selected from the group consisting of:


8. An organic electroluminescent device which comprises the combination according to claim 1, and emits yellow-green light. 